The climate crisis that the Earth is now facing has caused oceans to become warmer and more acidic, which in turn affects marine life. A major U.N. report released last week outlines how rising temperatures are killing off fish, which will soon lead to the extinction of many species, reported CNN.
Fish need oxygen to survive. As ocean temperatures warm, oxygen is depleted from the water, which in addition to more heatwaves and increased acidification, causes fish to move away from coastlines and create large deadzones where life is incapable of surviving.
Further complicating the problem is the presence of red algae blooms, which occur as water gets warmer. Also known as red tides, the algae further depletes oxygen from the water and kills off sea life. Red algae also releases a toxin that is present in seafood and can be poisonous to humans if consumed.
The report is troublesome at an international level, as many diets around the world depend on fish for survival. Fish provide up to half of all animal protein eaten in developing countries and is an important source of key vitamins and minerals.
“Projected decreases in seafood availability from climate impacts on fisheries catch potential will elevate the risk of nutritional health impacts,” the report warns.
A study in February of 2019 found that due to warming ocean waters, the world was experiencing a 4 percent global decline in sustainable catches, or the greatest number of fish that can be caught to prevent a long-term depletion of these fish in the ocean.
In addition to warming waters, ocean life is threatened by acidification. The report found that the ocean has taken up between 20 to 30 percent of the total human-produced carbon since the 1980s, which changes the chemistry of the water. Increased acidity threatens shellfish as it makes carbonate ions less abundant, which animals — such as oysters, mussels, and clams — need to build up their shells.
As acidification and ocean warming continue, the world will see more fish species become extinct, with remaining fish moving further away from the coasts. The report predicts that by 2100, the ocean will take up two to four times as much heat since 1970, while marine heatwaves will increase by a factor of 50 if carbon emissions aren’t reduced.
Malin Pinsky, an ecologist who studies marine communities, commented on what the report means.
“The key take away from this report is that fish in the ocean are the proverbial canary in the coal mine for climate impacts. This new report is a key step in helping everyone, including policymakers, understand exactly what could happen.”